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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 72 (1983), S. 161-171 
    ISSN: 1432-1424
    Keywords: erythrocytes ; membranes ; llama ; organization ; proteins ; band 3 ; cell shape ; deformability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The erythrocyte membrane of the llama was characterized in comparison to that of the human. The llama erythrocyte was an elliptical disk that resisted shape alterations in hyperosmotic buffers and following metabolic depletion, both of which induce spiculation of the human red cell. Lysophosphatidylcholine incorporation produced minor serrations of the edge of the llama disk but no spicules, whereas human red cells became sphero-echinocytes. The polypeptide profiles in the membranes of the two species were similar, except for several noteworthy differences: a marked elevation in the relative content of band 3; the absence of membrane-bound band 6; and simpler glycoprotein pattern in the llama. The concentration of band 3 in llama was about two and a half to three times that in the human and intramembrane particles in the protoplasmic leaflet of freeze-fractured llama membrane were correspondingly increased. The selective solubilization of bands 1, 2 and 5 in low ionic strength buffer, and all of the peripheral proteins in high alkaline buffer were similar except for increased retention of ankyrin by the llama membrane. These data suggest a similar disposition of membrane proteins. The llama membrane was markedly resistant to the solubilization of integral proteins by the nonionic detergent, Triton X-100. This property and the general resistance to shape changes may be related to the high concentration of band 3.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1424
    Keywords: cell shape control ; membrane skeleton ; lipid bilayer ; ligand-mediated agglutinability ; surface charge topography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Exposure of human erythrocytes to ethanol (1 to 20% by vol) in Ca2+ and Mg2+-free phosphate-buffered saline, pH 7.4, transformed biconcave discs into spiculated echinocytes within 3 min at 25°C. The effects of ethanol were concentration- and time-dependent, but reversible by washing in the incubation buffer system within 60 min of initial exposure to ethanol. After prolonged ethanol exposure (180 min), washing of cells resulted in the formation of stomatocytes (cup-forms). Ethanol-induced echinocytosis was also accompanied by a 30% enhancement in the agglutinability of erythrocytes by ligands with high affinity for negative surface charge (poly-l-lysine and wheat germ agglutinin, 20 μl/ml) without any alterations in surface charge topography. Concomitant exposure of erythrocytes to prostaglandin E1 (100nm) selectively prevented the enhancement of ligand-mediated agglutinability, but did not modify cell shape. These data indicate that certain erythrocyte surface properties may not be directly influenced by cell shape and suggest a unique modulatory action of prostaglandin E1 on shape-transformed cells.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 107 (1989), S. 213-218 
    ISSN: 1432-1424
    Keywords: acanthocytes ; bilayer ; cell shape ; chlorpromazine ; erythrocytes ; lipid ; McLeod ; membranes ; organization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary We have sought to elucidate the spiculated shape of McLeod erythrocytes. Red cells from a normal donor and from a McLeod patient were incubated in phosphate-buffered saline containing 0, 0.05, or 0.1mm chlorpromazine at 0°C for 5 min. then glutaraldehyde-fixed, and examined by scanning electron microscopy. The normal red cells were biconcave disks in which chlorpromazine induced inward (negative) curvature: deep cupping (stomatocytosis) and multiple invaginations. The McLeod cells were mostly spiculated. Chlorpromazine at lower concentration converted them into biconcave disks and, at higher concentration, into stomatocytes. These results support the hypothesis that the spiculation of McLeod cells is the result of an imbalance of surface area between the two lipid leaflets of the membrane; that is, a bilayer couple effect. We determined the numerical density of intramembrane particles (IMP) in replicas of both fracture faces of red cells subjected to freeze fracture and rotary shadowing. These values were as follows (expressed per μm2 of membrane ±sd): the normal protoplasmic fracture face had 2200±306 and the McLeod had 2300±250. The normal exoplasmic fracture face had 388±75 and the McLeod had 330±59. We conclude that there is no evidence for derangement of band 3, the principal protein in theIMP, in McLeod erythrocytes.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 8 (1978), S. 325-335 
    ISSN: 0091-7419
    Keywords: band 3 protein ; freez-fracture electron microscopy ; glyceraldehyde-3 phosphate dehydrogenase ; integral membrane protein ; intramembrane particle ; membrane proteins, unmasking ; spectrin ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The major red cell membrane protein, band 3, is a glycoprotein which extends across the membrane from the extracellular space into the cytoplasmic compartment. It is widely held that band 3 is a component of the intramembrane particles (IMP) which can be demonstrated by freeze-fracture electron microscopy. In this study, we find that the outer surface poles of the IMP can be seen by freeze-etching after they are unmasked by proteolysis under conditions which excise the surrounding sialopeptides from the membrane. The poles appear as distinctive projections, 30-50 Å in diameter, the “ES particles.” The ES particles remain associated with the outer surface of the membrane following cleavage of the band 3 polypeptide by chymotrypsin or pronase. This is consistent with previous biochemical studies which have shown that the 38,000-dalton outer surface segment of band 3 is intercalated in the lipid bilayer. A granulofibrillar component at the inner surface of the membrane is provisonally identified as the 40,000-dalton inner-surface domain of band 3.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 37 (1988), S. 213-223 
    ISSN: 0730-2312
    Keywords: retinoid ; lectin receptors ; selection ; flow cytometry ; lung colony formation ; reversible glycoconjugate modulation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Murine squamous carcinoma cells (KLN205) grown in a medium supplemented with the retinoid, 13-cis retinoic acid (RA), had dose-dependent, selective increases in the expression of certain lectin receptors, which correlated with a dramatic decrease in the ability to form pulmonary colonies (P -.0003) (Couch MJ, Pauli BU, Weinstein RS, Coon JS: JNCI, 78:971 -977, 1987). These findings suggest a possible relationship between the RA-induced glycoconjugate alterations and the decreased experimental metastatic behavior. We further define the mechanism of RA's action. The finding that RA treatment (5 × 10-6 M, 5 × 10-7 M) did not perturb the cell cycle of KLN205 cells provides further proof that the decreased metastatic behavior is not attributable to any inhibition in the rate of growth or to alterations in the cell cycle. Furthermore, since stable subpopulations with variable lectin binding could not be detected, the mechanism of RA's action does not appear to be due to selection of variant tumor-cell subpopulations. Finally, in a scries of experiments designed to determine the reversibility of the RA treatment, the RA-induced decrease in metastatic behavior reverted back to a more metastatic state in the same time frame (3 days) as the reversion of the RA-induced changes in cell-surface glycoconjugate expression. This reversion provides further evidence for a close relationship between the RA-induced modulation of tumor cell-surface glycoconjugate expression and the decreased metastatic behavior; it suggests that transient, reversible modulation of the tumor cell surface may play a role in determining metastatic behavior.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Publication Date: 1987-01-01
    Print ISSN: 0304-3991
    Electronic ISSN: 1879-2723
    Topics: Electrical Engineering, Measurement and Control Technology , Natural Sciences in General , Physics
    Published by Elsevier
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  • 7
    Publication Date: 1967-05-01
    Description: A simplified freeze-cleave and replication method of tissue preparation for examination in the electron microscope is applied to studies on red blood cell fine structure. With this technic, the cytoplasm of red blood cells appears to have a uniform pattern of packed granularity, with individual particles approximating the dimensions anticipated for replicas of individual hemoglobin molecules. The cell surface is smooth and partially covered with small particles which may represent antigens, enzymes, or some structural proteins. The possibility that particles seen in cells and on cell membranes may represent an artifact is discussed. Pretreatment of cells prior to freezing influences the plane of cleavage through packed cells so that the plane of cleavage can be preferentially directed either through the cytoplasm or along red cell membranes. The freeze-cleave technic may be of particular value in applications where extensive areas of membrane must be surveyed, such as searching for leukemogenic viruses budding through cell membranes.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
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  • 8
    Publication Date: 1967-12-01
    Description: Electron microscopic studies on dried isolated red cell ghosts have been reported to show lesions associated with cell membranes in paroxysmal nocturnal hemoglobinuria (PNH). In this study, carbon-platinum replicas of membranes of freeze-cleaved, partially hydrated PNH red cells and isolated PNH cell ghosts failed to confirm the existence of these abnormalities. This suggests that the previously described lesions are the products of drying artifacts, although they may reflect hidden structural differences between PNH and normal red cell membranes.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
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  • 9
    Publication Date: 1978-10-01
    Print ISSN: 0014-4827
    Electronic ISSN: 1090-2422
    Topics: Biology , Medicine
    Published by Elsevier
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  • 10
    Publication Date: 1981-11-01
    Print ISSN: 0014-4827
    Electronic ISSN: 1090-2422
    Topics: Biology , Medicine
    Published by Elsevier
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